DMX (digital multiplex) which is developed by (USITT) United States Institute for Theatre Technology is a communication protocol for controlling stage lighting. More specifically, most lighting control devices are compatible with DMX512.
DMX indicates that data is transmitted from lighting controllers to dimmers and lighting equipment, and allows up to 512 individual channels to be controlled via one signal line. DMX also illustrates asynchronous serial data carried at 250 KB/S (kilobytes per second). Moreover, DMX includes synchronous signals that have a low logic level (logic “0”) greater than 44 us (updates/second) followed by a high logic level (logic “1”) greater than 44 us and a start code. (For more information, please refer to the standard document introduced by USITT)
The ID address of the stage lighting is usually configured in advance, so the lighting device can receive the content for displaying based on the configured ID addresses. Traditionally, the addresses of devices are controlled by a DIP-Switch (dual in-line package switch) or are configured through communication transmission to configure each DMX control element's ID address. Referring to FIG. 1A, a schematic diagram illustrates the operation of conventional DMX512 lighting fixtures and signaling protocol. These three lighting device are connected in parallel, so all DMX512 lighting fixtures then receive the same signal shown in the FIG. 1B. The signal transmitted to these lighting devices includes an initial signal 14, ID0 data 11, ID1 data 12 and ID2 data 13, the lighting devices must be aware of the ID address corresponding to themselves in advance so as to accurately obtain data.
However, the lighting fixtures installed under water or mounted to external walls of buildings may cause inconvenience due to error ID configurations, and may not be easily disassembled.
To overcome the foregoing shortcomings, the inventor of the present invention based on years of experience to conduct extensive researches and experiment invents an address-free driving device and lighting fixture system, as a method or a basis.